This invention relates to aromatic sulfide polymers, more particularly poly(arylene sulfide) resins, and most particularly poly(phenylene sulfide) resins. More particularly, it relates to the treatment of these polymers to decrease the melt flow in an aspect of the invention that relates to the curing of arylene sulfide polymers by contact with oxygen. In still another aspect of the invention, it relates to the production of polymer which is characterized by a low-melt flow which provides high temperature stability to objects that have been molded from the resin.
U.S. Pat. No. 3,524,835 discloses that the contact of poly(arylene sulfide) resin heated to an elevated temperature above the melting point of the resin in an oxidizing atmosphere produces an increase in the molecular weight, i.e., a decrease of the melt flow of the polymer thustreated. The present invention provides a method that sets this knowledge to practical use by providing means that facilitate the contact of the polymer with oxygen under treating conditions. Such a process makes possible the degree of ease of operation that can lead to commercialization.
It is, therefore, an object of this invention to provide means for the facilitation of curing the resin, i.e., lowering the melt flow of poly(arylene sulfide) resin. It is another object of this invention to provide a method by which cured poly(arylene sulfide) resin can be produced that has sufficiently decreased melt flow properties to withstand high temperatures. It is still another object of this invention to provide a method for overcoming the practical difficulties of treating a material of increasing viscosity.
Other aspects, objects, and the various advantages of this invention will become apparent upon reading the specification and the appended claims.